Benign prostatic hyperplasia (BPH) refers to the enlargement of the prostate gland, which occurs in 50% of 60-year old men with increasing incidence with age. This unchecked growth is most likely caused by dihydrotestosterone (DHT), and it produces a decreasing quality of life because of deterioration of urinary flow rate, nocturia and acute urinary retention. While drugs are currently used to treat this condition, many men would prefer to use plant sterol-containing products because they have fewer side effects. Unfortunately, the sterols contained in many of these products are of questionable efficacy, most likely because they are insoluble in water and have variable bioavailability. By mixing plant sterols with lecithin, Lifeline Technologies, Inc. has shown that this combination renders lipid sterols dispersible in water, which enhances their biological activity. Importantly, this patented technology was used in preliminary studies to show that properly formulated plant sterols inhibit steroid 5 alpha reductase to lower DHT. Moreover, when delivered to men as a single dose in a breakfast drink, formulated sterols also lowered circulating DHT 4 hours after administration. Results from the clinical and biochemical experiments outlined herein will extend these studies. First, they will provide a quantitative description of the mechanism of inhibition between plant sterols and 5 alpha reductase. Second in a clinical trial, a complete time course of DHT suppression will be determined after sterol administration, providing the basis for a dose response curve. The work inititated here and pursued in a Phase II application will lead to a new, non-pharmaceutical approach for the treatment of BPH. Because of the acknowledged safety of plant sterols, the proposed product will be cost effective, free of side effects and available over the counter. Benign prostatic hyperplasia is a chronic condition that lowers the quality of life in older men by causing nocturia and deterioration of urinary flow rate. This proposal explores a formulation method for plant sterols that lowers blood levels of dihyrotestosterone, the presumed causative agent of the disease. Because of the acknowledged safety of plant sterols, the proposed product will be cost effective, free of side effects and available over the counter. [unreadable] [unreadable] [unreadable]